Wireless technology and services have grown exponentially over the past several years. As more and more people subscribe to wireless service, wireless service providers attempt to attract new subscribers and retain existing subscribers with unique features. Simultaneously, service providers generate revenue in proportion to subscribers' usage of the network and thereby desire to increase billable minutes on the network, both from individual subscribers and collectively from multiple subscribers.
A problem that arises is that mobile subscriber units can encounter periodic service interruption(s) during a call, for example, upon entering a tunnel or reaching a fringe RF coverage area, causing the mobile unit to become dropped (at least temporarily) from the call. In such case, other parties participating in the call (e.g., uninterrupted mobile units or wireline units) may terminate or “hang up” the call even though in some instances, service may be recovered to the mobile unit relatively quickly. Oftentimes, in such case, the parties do not re-attempt the call and, even if they do, one or more of the parties may be unavailable on the next attempt. Consequently, the conversation may never be completed. This represents both a source of frustration for subscribers and a lost opportunity cost for the service provider in terms of the additional minutes that might have been billed.
Accordingly, there is a need for a method for preserving calls when service is interrupted to a mobile unit. Advantageously, the method will increase customer satisfaction while simultaneously increasing the number of billable minutes on the network.